Device for converting solar energy

Abstract

A device is described for converting solar energy into electric power for a load, which device is provided with photocells and electric accumulators. Switching means are provided which at least during starting of the load connect this load to the output terminals of the array of photocells so that during starting the current through the load is determined by the current supplied by the photocells. The device makes efficient use of the available solar radiation, is of simple design and is reliable.

What is claimed is: 
     
       1. In a device for converting solar energy into electric energy to be supplied to a load of the type which exhibits an in-rush effect, the improvement comprising, a plurality of photocells for converting solar energy into electric energy, a plurality of electric accumulators for storing electric energy supplied by the photocells, the number of photocells being sufficient to provide a peak power and a peak photocell current which under optimum insolation is equal to or is slightly greater than the nominal power and the nominal current, respectively, of the load, means for coupling the photocells to the accumulators and the load, switching means for connecting the load, during the load starting period, to the photocells only so that the load current then is determined only by the photocell current, and detection means responsive to photocell current, load voltage and accumulator voltage for controlling the operation of said switching means. 
     
     
       2. A device as claimed in claim 1 further comprising second switching means responsive to an electric parameter associated with the photocells for selectively interconnecting the photocells and accumulators in series, in parallel, or in series-parallel circuit configurations as a function of said electric parameter. 
     
     
       3. A device as claimed in claim 1 wherein the load comprises an electric motor and said switching means includes first and second switching contacts connected respectively in a first series circuit that includes the photocells and the motor and in a second series circuit that includes the accumulators and the motor, said detection means being operative to control the switching means to close the first switching contact and open the second switching contact during the motor starting period when the in-rush effect occurs and then to close the second switching contact when the in-rush effect is terminated. 
     
     
       4. A power supply system comprising, first and second arrays of photocells for converting solar energy into electric energy, first and second electric accumulator means coupled to said first and second arrays of photocells, means for coupling a load to said photocell arrays and to said accumulator means, the number of photocells and their interconnections being arranged to provide a peak power and a peak photocell current which under optimum insolation is equal to or is slightly greater than the nominal power and the nominal current, respectively, of the load, detection means responsive to photocell current and load voltage, and switching means controlled by the detection means for connecting the load to the photocell arrays while simultaneously isolating the load from the accumulator means during a start-up period of the load whereby the load start-up current is limited to the current supplied by the photocells. 
     
     
       5. A power supply system as claimed in claim 4 wherein said detection means includes means for controlling the switching means to connect the load to the first and second accumulator means subsequent to the start-up period and for disconnecting the load from the photocell arrays below a given value of the photocell current. 
     
     
       6. A power supply system as claimed in claim 4 wherein said detection means is also responsive to the voltage of the accumulator means to control the switching means to connect the load to the photocell arrays above a given value of the accumulator voltage. 
     
     
       7. A power supply system as claimed in claim 6 wherein said detection means includes means responsive to the load voltage for controlling the switching means to connect the load to the first and second accumulator means subsequent to the start-up period and means responsive to the photocell current for disconnecting the load from the photocell arrays below a given value of the photocell current. 
     
     
       8. A power supply system as claimed in claim 4 wherein said switching means includes first and second switch contact means for selectively connecting the load to the photocell arrays and to the accumulator means, respectively, said detection means also including means responsive to the voltage of the accumulator means for controlling the switching means to close and open the first switch contact means above and below first and second given values of the accumulator voltage, respectively, said detection means including means responsive to the photocell current for controlling the switching means to close and open the first switch contact means above and below first and second given values of the photocell current, respectively, and said detection means further includes means responsive to the load voltage for controlling the switching means to close and open the second switch contact means above and below first and second given values of the load voltage, respectively. 
     
     
       9. A power supply system as claimed in claim 4 wherein the load comprises a motor or similar device and said switching means includes first and second switch contact means for selectively connecting the load to the photocell arrays and to the accumulator means, respectively, said detection means including means responsive to the voltage of the accumulator means and the photocell current for controlling the switching means to operate said first switch contact means as a function of the accumulator voltage and the photocell current, respectively, said detection means also including means responsive to the load voltage for controlling the switching means to operate said second switch contact means as a function of the load voltage.